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Workaround for blocked PyObject_GenericSetAttr in metatypes · pythonnet/pythonnet@92d9876 · GitHub
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Workaround for blocked PyObject_GenericSetAttr in metatypes
Python 3.14 introduced a new assertion that prevents us from using PyObject_GenericSetAttr directly in our meta type. To work around this, we manipulate the type dict directly. This workaround is a simplified variant of Cython's workaround from cython/cython#6325. The relevant Python change is in python/cpython#118454
1 parent 72eec81 commit 92d9876

5 files changed

Lines changed: 47 additions & 3 deletions

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‎src/runtime/Native/PyIdentifier_.cs‎

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@@ -22,6 +22,8 @@ static class PyIdentifier
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static IntPtr f__self__;
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public static BorrowedReference __self__ => new(f__self__);
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static IntPtr f__annotations__;
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public static BorrowedReference __dictoffset__ => new(f__dictoffset__);
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static IntPtr f__dictoffset__;
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public static BorrowedReference __annotations__ => new(f__annotations__);
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static IntPtr f__init__;
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public static BorrowedReference __init__ => new(f__init__);
@@ -54,6 +56,7 @@ static partial class InternString
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"__slots__",
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"__self__",
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"__annotations__",
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"__dictoffset__",
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"__init__",
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"__repr__",
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"__import__",

‎src/runtime/Native/PyIdentifier_.tt‎

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@@ -12,6 +12,7 @@
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"__slots__",
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"__self__",
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"__annotations__",
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"__dictoffset__",
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"__init__",
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"__repr__",

‎src/runtime/Types/MetaType.cs‎

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@@ -21,6 +21,7 @@ internal sealed class MetaType : ManagedType
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// set in Initialize
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private static PyType PyCLRMetaType;
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private static SlotsHolder _metaSlotsHodler;
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private static int TypeDictOffset = -1;
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#pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
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internal static readonly string[] CustomMethods = new string[]
@@ -35,6 +36,25 @@ internal sealed class MetaType : ManagedType
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public static PyType Initialize()
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{
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PyCLRMetaType = TypeManager.CreateMetaType(typeof(MetaType), out _metaSlotsHodler);
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// Retrieve the offset of the type's dictionary from PyType_Type for
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// use in the tp_setattro implementation.
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using (NewReference dictOffset = Runtime.PyObject_GetAttr(Runtime.PyTypeType, PyIdentifier.__dictoffset__))
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{
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if (dictOffset.IsNull())
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{
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throw new InvalidOperationException("Could not get __dictoffset__ from PyType_Type");
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}
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nint dictOffsetVal = Runtime.PyLong_AsSignedSize_t(dictOffset.Borrow());
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if (dictOffsetVal <= 0)
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{
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throw new InvalidOperationException("Could not get __dictoffset__ from PyType_Type");
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}
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TypeDictOffset = checked((int)dictOffsetVal);
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}
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return PyCLRMetaType;
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}
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@@ -44,6 +64,7 @@ public static void Release()
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{
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_metaSlotsHodler.ResetSlots();
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}
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TypeDictOffset = -1;
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PyCLRMetaType.Dispose();
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}
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@@ -287,7 +308,28 @@ public static int tp_setattro(BorrowedReference tp, BorrowedReference name, Borr
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}
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}
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int res = Runtime.PyObject_GenericSetAttr(tp, name, value);
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// Access the type's dictionary directly
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//
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// We can not use the PyObject_GenericSetAttr because since Python
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// 3.14 as https://github.com/python/cpython/pull/118454 intrdoduced
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// an assertion to prevent it from being called from metatypes.
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//
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// The direct dictionary access is equivalent to what Cython does
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// to work around the same issue: https://github.com/cython/cython/pull/6325
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BorrowedReference typeDict = new(Util.ReadIntPtr(tp, TypeDictOffset));
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int res;
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if (value.IsNull)
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{
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res = Runtime.PyDict_DelItem(typeDict, name);
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if (res != 0)
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{
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Exceptions.SetError(Exceptions.AttributeError, "attribute not found");
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}
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}
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else
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{
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res = Runtime.PyDict_SetItem(typeDict, name, value);
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}
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Runtime.PyType_Modified(tp);
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return res;

‎tests/test_array.py‎

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@@ -1348,7 +1348,6 @@ def test_special_array_creation():
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assert value.Length == 2
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@pytest.mark.skip
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def test_array_abuse():
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"""Test array abuse."""
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_class = Test.PublicArrayTest

‎tests/test_class.py‎

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@@ -236,7 +236,6 @@ def __setitem__(self, key, value):
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assert table.Count == 3
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@pytest.mark.skip
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def test_add_and_remove_class_attribute():
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from System import TimeSpan
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